Paint remover composition



Patented May 16, 1950 UNITED STATES PATENT OFFICE PAINT REMOV'ER COMPOSITION Lester E. Kuentzel, Wyandotte, Mich., assignor to Wyandotte Chemicals Corporation, Wyandotte, Mich., a corporation of Michigan N Drawing. Application November 1, 1945, Serial No. 626,174

1 Claim.

surface to which it is applied, is of course, the

most desirable property in a paint remover since it contributes not only to the reduction of time and labor required for stripping, but also to the general economy and efilciency of the remover in doing a given job.

Chlorinated aliphatic hydrocarbon solvents have heretofore been used and formulated to a considerable extent as ingredients of paint removers. I have made the discovery that in the case of certain particular aliphatic chlorinated hydrocarbon solvents, the presence of an acid greatly improves the stripping power of such solvents; and that most unexpectedly, the addition of a small amount of water to the acid and solvent imparts still greater stripping power.

Acids have not heretofore been regarded as possessing any paint stripping powers in and of themselves. Therefore, the presence of an acid in the particular solvents herein specified, is believed to function as a solvent activating catalyst, which results in the remarkably enhanced stripping power.

Additional objectives and advantages of my invention shall become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the following description sets forth in detail a method of procedure whereby those skilled in the art may be enabled readily to understand and practice the principle of my invention.

I have made the discovery that of the large number of chlorinated hydrocarbon solvents which have heretofore been employed in paint remover compositions, that only'a few of them respond to the activating influence of acid, or of water and an acid. Thus, for example, closely chemically related chlorinated hydrocarbons, such as 1,1,2-trichlorethane and trichlorethylene give just the opposite results, the former being greatly enhanced by the addition of an acid and/or water in its stripping power, and the latter failing to show any improvement. Accordingly, after extensive examination and testing of a, great many solvents, I have determined the following chlorinated aliphatic solvents to be those which have the unique property of responding to the activating influence of an acid and/or water in substantially enhancing their paint stripping ability:

Methylene chloride Ethylene dichloride 1,1,2-trichlorethane 1,1,2,2-tetrachlorethane Chloroform Ethylene chlorhydrin The following acids are those capable of i mparting an activating eifect on the stripping power of the above chlorinated solvents:

Formic Picric Acetic n-Propyl phosphoric Propionic Nitric Salicylic Benzoic Butyric Cinnamic Carbolic The amount of water incorporated into the mixture selected from the above solvents, and acids has been found to be critical. The amount of water should be no greater than that which is capable of going into solution with the remaining ingredients of the mixture. In other words, the mixture will remain in a single phase. If more than this maximum amount of water is added, not only will an emulsion be formed (i. e. two phases), which on standing and storage tends to separate out into layers, but also the stripping power of the composition will be decreased. As a practical criterion, the amount of water present in the formulations of solvents Additional ingredients such as a thickening agent, an evaporation retardant, a wettin agent and a blending agent may also be incorporated to advantage into the composition. As examples of a thickening agent, there can be mentioned methyl cellulose, corn starch, bentonite, ethyl cellulose and cellulose acetate. Paraffin wax recited in Navy Aeronautic Specification C-1l3, Amendment-2; and United States Army Air Force Test panels Nos. 14105 and 14109, as recited in Army Air Force Specification No. 14119. The detailed description of these stripping test panels is set forth in my co-pending application Serial No. 509,121, filed November 5, 1943.

Table I makes an excellent solvent evaporation retardant. Wetting agents of the alkyl aryl sulfonate type have been found to be quite satis factory in the formulation of compositions embodying the principle of my invention. Specifically, alkyl aryl sulfonate wetting agents are available on the market under the trade names of Santomerse D and Wetsit Concentrated. "Santomerse D is a substantially 99% dodecylbenzene sodium sulfonate. Wetsit Concentrated is a proprietary alkyl aryl sulfonate containing a minor proportion of terpenes and about water content. The alkyl and aryl groups of such latter form of alkyl aryl sulfona-te are not definitely known or publicized, such information being the private property of the manufacturer of such product. Wetsit Concentrated is particularly suitable since it contains approximately 20% water and thus serves as a convenient means for adding the water ingredient to the composition, making it unnececessary to add water separately as there is enough Water in such wetting agent to satisfy the formulation requirements.

The blending agent should be a co-solvent (such as methyl alcohol) for the thickening agent and the chlorinated aliphatic hydrocarbon. In the case of methyl cellulose as a thickening agent, an amine such as disclosed in my previously filed application Serial No. 509,121, fi ed November 5, 1943, now U. S. Pat. No. 2,433,517, issued Dec. 30, 1947, or one of the aliphatic alcohols or ethers disclosed in my co-pending application filed November 1, 1945, Serial No. 626,172 will be found the most satisfactory.

Generally outlined, the paint remover compositions of my invention are combined or formulated by mixing together the chlorinated solvent, the thickening agent, the acid, the water. and the blending agent in the order named and at room temperature. Melted paraffin wax, if present, is incorporated directly after the solvent.

The remarkable ability of relatively small amounts of water and acid to enhance or accelerate the stripping power of the chlorinated solvent, is shown in the following table where methylene chloride alone, and methylene chloride containing water and salicylic acid (separately and jointly), was applied to U. S. Navy A ronautical Specification test panels 72 and 75E as The following table shows the remarkable manner in which the addition of a small amount of acid (1% by volume, chlorinated solvent basis, in the examples given) and a small amount of water (0.5 to 2% by volume, chlorinated solvent basis, in the examples given) enhances the stripping power of the chlorinated hydrocarbon solvents. The acetic acid ingredient employed in the formulations of this table is in the form of glacial acetic acid, and the formic acid is in the form of a 90% (by weight) formic acidwater solution.

Table II Stripping Power (time in seconds required to Formm lolosteiii coattintg 001111- v peeyon es panes 1:13:18 Constituents (parts by volume) #14105 and #1409) 1116 Methylene Chloride 10 and Acetic Acid 0.1 1,500 1187 Methylene Chloride 10, Acetic Acid 0.1 and Water 0.1 20 1164 Methylene Chloride l0, Formic Acid 0.1 and Water 0.1 10 50 1381 Ethylene Dichloride (alone). (Over) 1,800 1396 Ethylene Dichloride 10, Fornn Acid 0.1 and water .05 360 1391 Ethylene Dicholride l0 and Formic Acid 0.1 480 1384 1,1,2-Trichlorethane (alone) (over) 1,800 1394 1,1,2-Triel1lorethane 10 and Formic Acid 0.1 l, 200 1390 1,1,2-Triehlorethane 10 Formic Acid 0.1 and Water 05 900 1382 l,l,2,2-Tetrachloretl1ane (alone) (over) 1,800 1392 1,1,2,2-Tetraehlorethane 10 and Formic Acid 0.1 l, 200 1397 l,1,2,2-Tetrachlorethane 10, Formic Acid 0.1 and Water .05-.-.. 720 1385 Chloroform (alone) (over) 1,800 1395 Chloroform 10 and Formic Acid 360 fl 1 1400 Chloroform l0, Formic Acid 0.1

and Water .05 250 In the above table where the stripping power of the respective solvents alone is noted as over '1800 seconds or 30 minutes, the test panel was not completely stripped. That is to say the coating was merely softened or partially loosened. However, in the case of all the other figures given in Table II, the coating was completely loosened and ready to fall off the panel, in the time periods given.

As the following examples of formulations of ingredients further serve to illustrate my invention, these examples,'however, not being intended as limitations of the scope of my invention:

The foregoing constituents were combined by mixing together in the order given above at room temperature, with the exception of paraflln wax which was melted prior to introduction into the mixture. The resulting composition possesses thixotropic properties, i. e. is fluid when agitated and gelled and immobile when applied to the surface from which the coating is to be removed. It is amber in color and smooth in texture. The formulation of Example 1 completely loosened the coating in seconds from U. S. Navy Aeronautical Speciflcation test panels 70E, '72 and 75E; completely loosened the coating from U. S. Army Air Force test panels Nos. 14105 in seconds and 14109 in 70 seconds.

Example 2 The resulting composition of the above example is thixotropic, blue in color and smooth in texture. Its stripping power is illustrated by the following test results:

Time in Panel Seconds amber in color. It completely loosened thecoating from test panel No. 14109 in 40 seconds.

Example 4 [Formulation No. 1376] Per Cent Per Cent. Amount by H1O Weight Content 'letrachlorethane (Technical) 80. 46 Pareflin 0. 56

Methyl Cellulose (4000 cps.) Wetsit Concentrated (20% The paint remover composition of this example is amber in color, slightly viscous, transparent and smooth in texture. It stripped the coating from test panel No. 14109 in seconds.

Example 5 [Formulation No. 1374] l, 1, Z-Trichlorethane. araflin Methyl Cellulose (4000 cps). Wetsit Concentrated Hi0) Acetic Acid (Glacial)- Formic Acid (90%) Methyl Alcohol The paint remover composition of the foregoing example is amber in color, slightly viscous, transparent and smooth in texture. It completely loosened the coating from test panel No. 14109 in '70 seconds.

Example 6 [Formulation No. 1377] Methyl Alcohol I This formulation is amber in color, slightly viscous and transparent. The stripping test showed removal of coating from test panel No. 14109 in 40 seconds.

Example 3 Example 7 [Formulation No. 1370] [Formulation No. 1379] Per Cent Per Cent Per Cent Per Cent Amount H10 Con- 5 Amount by H40 by weight tent 6 Weight Content Ethylene Dichloride 87. 05 Ethylene Chlorhydrin. 86. 64 Paraflin 0.69 Paraflin 1 0. 71 Methyl Cellulose (4000 cps. 0.69 Methyl Cellulose (4000 cps. 0. 71 Wetsit Concentrated (20% 3. 48 WetsitConcentrated(20% H10)- 3. 57 0. 714 Acetic Acid (Glacial) 0. 76 Acetic Acid (Glacial) 0. 79 Formic Acid (90%). 0. 76 Formic Acid (90%)-. 0. 79 0. 079 Methyl Alcohol 6. 57 Methyl Alcohol 6. 79 100.00 100. 00 0. 793

The above formulation is slightly viscous and 1 The composition resulting from this formulation is amber .in-color,-slightly viscous and transparent, showing a stripping power on test :panel No. 14109 of 300 seconds.

The unpredictable and unexpected results of the present invention will become more readily apparent, when it is noted that a mixture of ethylene dichloride parts and acetic acid 0.1 (-by volume) stripped test panel No. 14109 in 8 minutes, whereas a comparable mixture of ethylene trichloride (trichlorethylene) 10 parts and acetic acid 0.1'part, required over minutes to strip the same panel. Therefore, the catalytic or activating abilityof the acid is quite selective and dependent upon the combination with the particular chlorinated aliphatic hydrocarbon solvents which I have herein disclosed and hereinafter claim as within the scope of my invention.

Equivalent modes of practicing my invention may'be followed provided that theyare within the scope and purview of the appended claim.

I, therefore, distinctly claim and particularly point out as my invention:

A paint remover composition consisting essentially of a solvent selected from the group consisting of methylene chloride,ethylene dichloride, 1,1 ,2 -trichlore'thane, 1,1,2,2 tetrachlorethane,

81 chloroform and ethylene chlorhydrin; 0.1-% by weight of a mixture of approximately equal parts of concentration formic acid and concentration acetic acid, and 0.016% by weight of water.

LESTER E. KUENTZEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 309,655 Scott Dec. 23, 1884 1,095,270 Ellis May 5, 1914 1,147,850 Ellis July 27, 1915 1,406,175 Ellis Feb. 14, 1922 1,918,224 Wilson July 11,1933 1,974,744 Klinkenstein Sept. '25, 1934 1,993,096 Hodges Mar. 5, 1935 2,418,138 Packer Apr. 1, 1947 FOREIGN PATENTS Number Country Date 485,857 Great Britain May 20, 1938 Certificate of Correction Patent No. 2,507,985 May 16, 1950 LESTER E. KUENTZEL It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, Example 4, first column of the table, for Ethyl Alcohol read Methyl Alcohol;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 15th day of August, A. D. 1950.

[men] THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents. 

